Patch Antenna

Abstract

The purpose of the present invention is to provide a patch antenna, a method, and a program that are capable of easily matching the input impedance of the patch antenna to a prescribed frequency. A patch antenna (10) according to the present disclosure is provided with: a microstrip line (12) that is provided on a liquid crystal (11), that extends in a first direction (D1), and that allows a signal to pass therethrough; a dielectric (13) provided on the microstrip line (12); a patch antenna element (14) that is provided on the dielectric (13) and that emits a signal by acquiring the signal from the microstrip line (12) in an electromagnetically coupled manner; and a control unit (15) for matching the input impedance of the patch antenna (10) at a prescribed frequency by changing the dielectric constant of the liquid crystal (11) on the basis of a voltage applied to the liquid crystal (11).

Description

[Technical field]

[0001] The present disclosure relates to a patch antenna, a method, and a program, and more particularly to a patch antenna, a method, and a program that can easily match the input impedance of a patch antenna at a predetermined frequency. [Background technology]

[0002] In general, in order to improve the efficiency of transmission and reception of an antenna, it is necessary to match the input impedance when a signal is input from a transmission line to an antenna to a specified frequency. There are three main methods for matching the input impedance. The first method is to match the impedance by changing the shape of the antenna. For example, a dipole antenna has a characteristic that the matching frequency changes when the linear part of the antenna is bent midway. By utilizing this characteristic, the input impedance is matched to a specified frequency by optimizing the position and angle at which the dipole antenna is bent. However, in the first method, when changing the frequency to be matched to a specified frequency, it is necessary to physically change the bending position of the antenna, etc., and there is a problem that it is difficult to easily change the frequency to be matched. The second method is to match the impedance by changing the feeding point of the antenna. However, in the second method, when changing the frequency to be matched to a specified frequency, it is necessary to physically change the feeding point of the antenna, and there is also a problem that it is difficult to easily change the frequency to be matched. The third method is to match the impedance using a matching device. Specifically, a matching box is provided between the antenna and the power supply cable, and the impedance of the matching box is changed to match the impedance of the antenna. The third method has the problem that the area around the antenna increases in size due to the matching box, and the cost increases due to the matching box. The circuit that constitutes the matching box is sometimes called a matching circuit.

[0003] Paragraphs 0019 and 0020 of Patent Document 1 state that "the power supply unit is disposed on the first surface of the matching circuit board, which is the same as the surface on which the antenna unit is disposed, and the power supply unit is electrically connected to the antenna unit via a transmission line. The transmission line is disposed on the first surface of the matching circuit board. The transmission line extends, for example, linearly and is disposed between the power supply unit and the antenna unit. One end of the transmission line is electrically connected to the power supply unit, and the other end is electrically connected to the antenna unit." Furthermore, paragraphs 0042 and 0043 of Patent Document 1 state that "the permittivity control unit includes, for example, a power supply unit and a control circuit, and its positive electrode is electrically connected to the permittivity variable unit via an application electrode and applies a voltage to the permittivity variable unit. As a result, the permittivity control unit performs variable control of the permittivity of the permittivity variable unit. According to the configuration of the second embodiment, the permittivity of the permittivity variable unit can be controlled, so that it is possible to adjust the matching conditions for impedance matching. Therefore, it is possible to realize even more suitable impedance matching." Patent Document 1 does not disclose transmitting a high-frequency signal from a microstrip line to a patch antenna element by electromagnetic coupling and optimizing the voltage applied to the liquid crystal to match the input impedance at a predetermined frequency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-10125 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, it is difficult to change the input impedance of the antenna, and it is difficult to easily match the input impedance of the antenna at a predetermined frequency. In addition, when a matching device is used, the size of the device increases and the cost increases.

[0006] An object of the present disclosure is to provide a patch antenna, a method, and a program that solves any of the above-mentioned problems. [Means for solving the problem]

[0007] The patch antenna according to the present disclosure comprises: a microstrip line provided on the liquid crystal, extending in a first direction, and transmitting a signal; a dielectric provided on the microstrip line; a patch antenna element provided on the dielectric material, which receives the signal from the microstrip line by electromagnetic coupling and radiates the signal; a control unit that changes the dielectric constant of the liquid crystal based on a voltage applied to the liquid crystal to match the input impedance of the patch antenna at a predetermined frequency; Equipped with.

[0008] The method according to the present disclosure comprises: A method for controlling an input impedance of a patch antenna including a microstrip line provided on a liquid crystal, extending in a first direction, and transmitting a signal, a dielectric provided on the microstrip line, and a patch antenna element that acquires the signal from the microstrip line by electromagnetic coupling and radiates the signal, comprising: Varying the dielectric constant of the liquid crystal based on a voltage applied to the liquid crystal; changing the dielectric constant of the liquid crystal to match the input impedance of the patch antenna at a predetermined frequency; Equipped with.

[0009] The program according to the present disclosure is A program for controlling an input impedance of a patch antenna including a microstrip line provided on a liquid crystal, extending in a first direction, and transmitting a signal, a dielectric provided on the microstrip line, and a patch antenna element that acquires the signal from the microstrip line by electromagnetic coupling and radiates the signal, Varying the dielectric constant of the liquid crystal based on a voltage applied to the liquid crystal; changing the dielectric constant of the liquid crystal to match the input impedance of the patch antenna at a predetermined frequency; to be executed by the computer. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a patch antenna, a method, and a program that can easily match the input impedance of a patch antenna at a predetermined frequency. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view illustrating a patch antenna according to a first embodiment. [Diagram 2] 1 is a schematic diagram illustrating a configuration of a patch antenna according to a first embodiment. [Diagram 3] 4 is a graph illustrating the operation of the patch antenna according to the first embodiment. [Figure 4] 4 is a graph illustrating the operation of the patch antenna according to the first embodiment. [Diagram 5] 4 is a schematic diagram illustrating the configuration of a patch antenna according to a comparative example of the first embodiment. FIG. [Figure 6] 11 is a perspective view illustrating a transmission line of a patch antenna according to a second embodiment. FIG. [Figure 7] 11 is a perspective view illustrating a transmission line of a patch antenna according to a second embodiment. FIG. [Figure 8] 11 is a perspective view illustrating a patch antenna according to a second embodiment. FIG. [Figure 9] 11 is a perspective view illustrating a transmission line of a patch antenna according to a third embodiment. FIG. [Figure 10] 13 is a graph illustrating the operation of the patch antenna according to the third embodiment. [Figure 11] 13 is a graph illustrating the operation of the patch antenna according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding elements are given the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0013] [Embodiment 1] <Antenna configuration> FIG. 1 is a perspective view illustrating a patch antenna according to the first embodiment. FIG. 2 is a schematic diagram illustrating the configuration of the patch antenna according to the first embodiment. 2, the dielectric and the liquid crystal are separated in order to show the configuration of patch antenna 10 according to embodiment 1 in more detail. That is, the dielectric and the liquid crystal of patch antenna 10 are originally in contact with each other as shown in FIG.

[0014] As shown in FIGS. 1 and 2, patch antenna 10 according to the first embodiment includes liquid crystal 11, a microstrip line 12, a dielectric 13, a patch antenna element 14, and a control unit 15.

[0015] The microstrip line 12 is provided on the liquid crystal 11. The microstrip line 12 extends in a first direction D1, and a signal is transmitted through the microstrip line 12. Since the signal transmitted is a high-frequency signal, this signal may also be referred to as a high-frequency signal. The microstrip line may also be simply referred to as a transmission line.

[0016] The dielectric 13 is provided on the microstrip line 12 .

[0017] The patch antenna element 14 is provided on the dielectric material 13. The patch antenna element 14 receives a signal from the microstrip line 12 by electromagnetic coupling, and radiates the received signal from the patch antenna element 14 itself.

[0018] The control unit 15 changes the dielectric constant of the liquid crystal 11 based on the voltage applied to the liquid crystal 11. By changing the dielectric constant of the liquid crystal 11, the control unit 15 matches the input impedance of the patch antenna 10 at a predetermined frequency.

[0019] Specifically, when the input impedance of patch antenna 10 at a predetermined frequency is within a predetermined impedance range, control unit 15 determines that the input impedance is matched. Matching is also called "matching."

[0020] A method for applying a voltage to the liquid crystal 11 will now be described. 2, a negative electrode 16 is provided so as to be in contact with the lower surface of the liquid crystal 11, and a positive electrode 17 is provided so as to be connected to the microstrip line 12. The control unit 15 generates a voltage using the positive electrode 17 and the negative electrode 16, and applies the voltage to the liquid crystal 11. The negative electrode is sometimes called a ground.

[0021] <Antenna operation> FIG. 3 is a graph illustrating the operation of the patch antenna according to the first embodiment. The horizontal axis in FIG. 3 indicates frequency, and the vertical axis indicates input reflection coefficient S11. FIG. 4 is a graph illustrating the operation of the patch antenna according to the first embodiment. The horizontal axis in FIG. 4 indicates frequency, and the vertical axis indicates input reflection coefficient S11. 3 and 4 show frequency characteristics of the input reflection coefficient S11 when the voltage applied to the liquid crystal 11 is changed.

[0022] In the patch antenna 10, by matching the impedance of the microstrip line 12 to the impedance of the patch antenna element 14, signal reflection from the patch antenna element 14 is reduced, resulting in a lower input reflection coefficient S11. In this way, matching the impedance is equivalent to lowering the input reflection coefficient S11. Therefore, here, impedance matching is shown as the input reflection coefficient S11 being equal to or lower than a predetermined reflection coefficient.

[0023] 3, when the voltage applied to the liquid crystal 11 is increased from voltage V31 to voltage V33 via voltage V32, the frequency characteristic of the input reflection coefficient S11 moves from graph G31 to graph G33 via graph G32. The reason for this is that changing the voltage applied to the liquid crystal 11 changes the dielectric constant of the liquid crystal 11, which changes the wavelength shortening rate when a signal is transmitted through the microstrip line 12, and as a result, the frequency range in which the input reflection coefficient S11 is equal to or lower than a predetermined reflection coefficient changes.

[0024] In this way, the patch antenna 10 according to the first embodiment can control the frequency at which the input impedance of the patch antenna 10 is matched over the frequency range BW by changing the voltage applied to the liquid crystal 11 by the control unit 15 (see FIG. 3). For example, when the control unit 15 desires an input reflection coefficient S11 as shown in graph G31, the control unit 15 sets the voltage applied to the liquid crystal 11 to voltage V31. Also, for example, when the control unit 15 desires an input reflection coefficient S11 as shown in graph G32, the control unit 15 sets the voltage applied to the liquid crystal 11 to voltage V32. Also, for example, when the control unit 15 desires an input reflection coefficient S11 as shown in graph G33, the control unit 15 sets the voltage applied to the liquid crystal 11 to voltage V33.

[0025] According to the first embodiment, a wideband antenna that supports the frequency range BW can be realized without a matching device. As a result, a patch antenna, a method, and a program that can easily match the input impedance of the patch antenna at a predetermined frequency can be provided.

[0026] 4, when an input reflection coefficient S11 as shown in graph G41 is desired, that is, when the frequency range BW1 is the frequency range in which the input reflection coefficient S11 is equal to or smaller than a predetermined input reflection coefficient, control unit 15 sets the voltage to be applied to liquid crystal 11 to voltage V41. When an input reflection coefficient S11 as shown in graph G42 is desired, that is, when the frequency range BW2 is the frequency range in which the input reflection coefficient S11 is equal to or smaller than a predetermined input reflection coefficient, control unit 15 sets the voltage to be applied to liquid crystal 11 to voltage V42.

[0027] As a result, according to the first embodiment, an antenna that supports dual bands of frequency range BW1 or frequency range BW2 can be realized without a matching device. However, one patch antenna 10 does not support both frequency range BW1 and frequency range BW2 at the same time.

[0028] Furthermore, according to the first embodiment, the shape of patch antenna 10 is not changed, so there is little effect on the directivity (gain) of the antenna.

[0029] Moreover, according to the first embodiment, since a matching unit is not used, the device including patch antenna 10 can be made smaller in size, and costs can be reduced by the amount that a matching unit is not used.

[0030] <Features> Here, the features of patch antenna 10 according to the first embodiment will be described below. The patch antenna 10 has liquid crystal 11 placed under a microstrip line 12 (transmission line) and can match impedance at a desired frequency by applying a voltage to the liquid crystal 11 to change the dielectric constant of the liquid crystal 11.

[0031] Furthermore, patch antenna 10 transmits a high-frequency signal from microstrip line 12 to patch antenna element 14 by electromagnetic coupling, and optimizes the voltage applied to liquid crystal 11 to match the input impedance at a predetermined frequency.

[0032] [Comparative Example] FIG. 5 is a schematic diagram illustrating the configuration of a patch antenna according to a comparative example of the first embodiment.

[0033] As shown in FIG. 5, patch antenna 50 according to the comparative example differs from patch antenna 10 according to the first embodiment in that a dielectric 51 is mounted under microstrip line 12 instead of liquid crystal 11.

[0034] Since the patch antenna 50 does not have the liquid crystal 11 mounted thereon, the dielectric constant of the dielectric 51 cannot be changed. Since the dielectric constant of the patch antenna 50 cannot be changed, the impedance frequency characteristic cannot be changed, and it is difficult to match the input impedance at a predetermined frequency. It is also difficult to make it broadband. As a result, it is difficult to provide a patch antenna that can easily match the input impedance of the patch antenna at a predetermined frequency.

[0035] [Embodiment 2] <Antenna configuration> FIG. 6 is a perspective view illustrating a transmission line of the patch antenna according to the second embodiment. FIG. 7 is a perspective view illustrating a transmission line of the patch antenna according to the second embodiment. 6 and 7, for simplicity, the dielectric body 13 and the patch antenna element 14 are omitted.

[0036] As shown in FIG. 6, the patch antenna 20 according to the second embodiment differs from the patch antenna 10 according to the first embodiment in that a meandering transmission line 12m is used instead of the microstrip line 12.

[0037] Also, as shown in FIG. 7, the patch antenna 20 according to the second embodiment differs from the patch antenna 10 according to the first embodiment in that a spiral transmission line 12s is used instead of the microstrip line 12.

[0038] FIG. 8 is a perspective view illustrating a patch antenna according to the second embodiment. In order to show the configuration of patch antenna 20 according to embodiment 2 in more detail, the dielectric and liquid crystal are separated in Fig. 8. For simplicity, control unit 15, negative electrode 16, and positive electrode 17 are omitted in Fig. 8. Fig. 8 shows meander type transmission line 12m as a signal transmission line.

[0039] 8, in the patch antenna 20 according to the second embodiment, the number of meander-type transmission lines 12m may be at least one or more, and the number of spiral-type transmission lines 12s may be at least one or more.

[0040] 8 shows four patch antenna elements 14 and four corresponding meander-type transmission lines 12m, but is not limited to this. The patch antenna 20 according to the second embodiment may have a number other than four patch antenna elements 14 and a number other than four meander-type transmission lines 12m.

[0041] Furthermore, the transmission line according to the second embodiment may be a planar transmission line other than the microstrip line 12, the meander type transmission line 12m, and the spiral type transmission line 12s.

[0042] [Embodiment 3] <Antenna configuration> FIG. 9 is a perspective view illustrating a transmission line of the patch antenna according to the third embodiment. For simplicity, the dielectric body 13 and the patch antenna element 14 are omitted from FIG.

[0043] 9, the patch antenna 30 according to the third embodiment differs from the patch antenna 10 according to the first embodiment in that it further includes a first ground line 121 and a second ground line 122. A line including the microstrip line 12, the first ground line 121, and the second ground line 122 is referred to as a coplanar line 12c.

[0044] The first ground line 121 is provided on the liquid crystal 11 in a second direction D2 intersecting the first direction D1 of the microstrip line 12, and extends in the first direction D1. That is, the first ground line 121 is provided in a position substantially parallel to the microstrip line 12. The length of the first ground line 121 in the first direction D1 is shorter than the length of the microstrip line 12 in the first direction D1. The first ground line 121 and the negative electrode 16 are electrically connected.

[0045] The second ground line 122 is provided on the liquid crystal 11 in the opposite direction to the second direction D2 of the microstrip line 12, and extends in the first direction D1. That is, the second ground line 122 is provided in a position substantially parallel to the microstrip line 12. The length of the second ground line 122 in the first direction D1 is shorter than the length of the microstrip line 12 in the first direction D1. The second ground line 122 and the negative electrode 16 are electrically connected.

[0046] Moreover, the difference between the length in the first direction D1 of the first ground line 121 and the length in the first direction D1 of the second ground line 122 is set to a predetermined length or less. In other words, the length of the first ground line 121 and the length of the second ground line 122 are set to be approximately the same length.

[0047] Coplanar line 12c can obtain the same effect as a coaxial cable by using microstrip line 12, first ground line 121, and second ground line 122, and feed point P shown in FIG. 9 serves as a pseudo feed point. The position of pseudo feed point P of coplanar line 12c can be changed by changing the lengths of first ground line 121 and second ground line 122. Changing the position of feed point P can change the frequency at which impedance is matched. Therefore, by using coplanar line 12c, impedance matching can be performed even more easily.

[0048] It is considered that the microstrip line 12 corresponds to the inner conductor of a coaxial cable, and the first ground line 121 and the second ground line 122 correspond to the outer conductor of the coaxial cable.

[0049] <Antenna operation> FIG. 10 is a graph illustrating the operation of the patch antenna according to the third embodiment. The horizontal axis in FIG. 10 indicates frequency, and the vertical axis indicates input reflection coefficient S11. FIG. 10 shows the frequency characteristics of the input reflection coefficient S11 when the length L (see FIG. 9) of the first ground line 121 and the second ground line 122 is changed.

[0050] 10, when the length L of the first ground line 121 and the second ground line 122 is changed from an arbitrary length L101 to an optimal length L102, the graph moves from G101 to G102. This lowers the input reflection coefficient S11 and expands the frequency range below a certain input reflection coefficient.

[0051] FIG. 11 is a graph illustrating the operation of the patch antenna according to the third embodiment. The horizontal axis in FIG. 11 indicates frequency, and the vertical axis indicates input reflection coefficient S11. FIG. 11 shows the frequency characteristics of the input reflection coefficient S11 when the voltage applied to the liquid crystal 11 is changed.

[0052] As shown in Fig. 11, when the length L of the first ground line 121 and the second ground line 122 is changed from an arbitrary length L101 to an optimal length L102, the graph moves from G111 to G112. This lowers the input reflection coefficient S11 and expands the frequency range below a predetermined reflection coefficient. The explanation up to this point is the same as that shown in Fig. 10. However, the voltage applied to the liquid crystal 11 is a voltage V112.

[0053] In this state, when the voltage applied to the liquid crystal 11 is increased from voltage V112 to voltage V113, the curve moves from G112 to G113. In this way, even in the patch antenna 30 having the coplanar line 12c, the input impedance can be easily matched at a predetermined frequency.

[0054] In the above embodiment, the present invention has been described as being configured as hardware, but the present invention is not limited to this. The present invention can also be realized by having a CPU (Central Processing Unit) execute a computer program to process each component.

[0055] In the above embodiment, the program can be stored and supplied to the computer using various types of non-transitory computer readable media. The non-transitory computer readable media includes various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (specifically, flexible disks, magnetic tapes, and hard disk drives), magneto-optical recording media (specifically, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, semiconductor memories (specifically, mask ROMs, PROMs (Programmable ROMs), and EPROMs (Erasable PROMs)), flash ROMs, and RAMs (Random Access Memory). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of the transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer readable media can supply the program to the computer via wired communication paths such as electric wires and optical fibers, or wireless communication paths.

[0056] Additionally, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order depicted, or that all of the depicted operations be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Similarly, although details of several specific embodiments are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable combination.

[0057] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0058] Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention.

[0059] This application claims priority based on Japanese Patent Application No. 2021-057098, filed on March 30, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0060] 10, 20, 30, 50: Patch antenna 11: Liquid crystal 12: Microstrip line 12m: Meander-type transmission line 12s: Spiral transmission line 12c: Coplanar line 121: First ground line 122: Second ground line 13: Dielectric 14: Patch antenna element 15: Control unit 16: Negative electrode 17: Positive electrode 51: Dielectric D1: 1st direction D2:Second direction D3: Third direction BW, BW1, BW2: Frequency range G31, G32, G33, G41, G42, G101, G102, G111, G112, G113: Graph V31, V32, V33, V41, V42, V112, V113: Voltage S11: Input reflection coefficient P: Pseudo power supply point L, L101, L102: Length

Claims

1. A patch antenna, a microstrip line sandwiched between a liquid crystal and a dielectric, extending in a first direction, and transmitting a signal; a patch antenna element provided on an opposite side of the microstrip line with the dielectric therebetween, the patch antenna element receiving the signal from the microstrip line by electromagnetic coupling and radiating the signal; a first ground line and a second ground line which are provided on the same plane on the liquid crystal surface, on both ends of the microstrip line, and which are arranged in parallel with the microstrip line and extend in the first direction; Equipped with a length of the first ground line in the first direction is shorter than a length of the microstrip line in the first direction; a length of the second ground line in the first direction is shorter than a length of the microstrip line in the first direction; By changing the dielectric constant of the liquid crystal based on the voltage applied to the liquid crystal, the input impedance of the patch antenna is matched at a predetermined frequency. Patch antenna.

2. a difference between a length of the first ground line in the first direction and a length of the second ground line in the first direction is equal to or less than a predetermined length; The patch antenna of claim 1 .

3. If the input impedance of the patch antenna at the predetermined frequency is within a predetermined impedance range, the input impedance is determined to be matched. The patch antenna of claim 1 .

4. a negative electrode provided in contact with a lower surface of the liquid crystal; A positive electrode provided to be connected to the microstrip line; Further equipped with The voltage is applied to the liquid crystal using the positive electrode and the negative electrode. The patch antenna of claim 1 .

5. A patch antenna, A meander-type transmission line that transmits signals through a liquid crystal and a dielectric material. a patch antenna element provided on an opposite side of the meander-type transmission line with the dielectric therebetween, the patch antenna element receiving the signal from the meander-type transmission line by electromagnetic coupling and radiating the signal; Equipped with By changing the dielectric constant of the liquid crystal based on the voltage applied to the liquid crystal, the input impedance of the patch antenna is matched at a predetermined frequency. Patch antenna.

6. The number of the meander type transmission lines is at least one. The patch antenna according to claim 5 .

7. If the input impedance of the patch antenna at the predetermined frequency is within a predetermined impedance range, the input impedance is determined to be matched. The patch antenna according to claim 5 .

8. a negative electrode provided in contact with a lower surface of the liquid crystal; a positive electrode provided to be connected to the meander-type transmission line; Further equipped with The voltage is applied to the liquid crystal using the positive electrode and the negative electrode. The patch antenna according to claim 5 .

9. A patch antenna, A spiral transmission line that transmits signals through a liquid crystal and a dielectric material. a patch antenna element provided on an opposite side of the spiral transmission line with the dielectric therebetween, the patch antenna element receiving the signal from the spiral transmission line by electromagnetic coupling and radiating the signal; Equipped with By changing the dielectric constant of the liquid crystal based on the voltage applied to the liquid crystal, the input impedance of the patch antenna is matched at a predetermined frequency. Patch antenna.

10. The number of the spiral transmission lines is at least one. The patch antenna of claim 9.

11. If the input impedance of the patch antenna at the predetermined frequency is within a predetermined impedance range, the input impedance is determined to be matched. The patch antenna of claim 9.

12. a negative electrode provided in contact with a lower surface of the liquid crystal; a positive electrode provided to be connected to the spiral transmission line; Further equipped with The voltage is applied to the liquid crystal using the positive electrode and the negative electrode. The patch antenna of claim 9.

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